Unfractionated heparin

General

• Type: Anticoagulant
• Dosage Forms: IV, SC
• Common Trade Names: Heparin

Adult Dosing

• See University of Washington pharmacy heparin infusion guidelines

Thromboembolism

• Bolus: 80 units/kg IV x 1 (MAX: 5,000 units)
• Then drip: 18 units/kg/h IV (MAX: 1,000 units/h)
• Adjust dose to target aPTT levels based on nomogram

Pediatric Dosing

• IV infusion
  • Initial loading dose 75 units/kg given over 10 minutes
  • Initial maintenance dose 20 units/kg/hour and adjest per local policy

Special Populations

• Pregnancy Rating: C
• Lactation risk: Infant risk minimal
• Renal Dosing
  • No adjustment
• Hepatic Dosing
  • No adjustment

Contraindications

• Allergy to class/drug
• 33% of patients develop some form of bleeding complication; 2-6% develop major bleeding
• HIT (Heparin-Induced Thrombocytopenia)

Risk Factors for Major Bleeding Complication

• Recent surgery or trauma
• Renal failure
• Alcoholism
• Malignancy
• Liver failure
• Concurrent use of warfarin, fibrinolytics, steroids, or antiplatelet drugs

Adverse Reactions

Serious

• Major bleeding
• Thrombocytopenia

Common

• Injection site reactions
• Hyperkalemia
• Alopecia
• Osteoporosis

Pharmacology

• Half-life: 1.5 hrs
• Metabolism: Hepatic
• Excretion: Urine
• Mechanism of Action:
  • Binds to and activates antithrombin which in turns inactivates factor Xa and thrombin
• Anticoagulation effect lasts up to 3hr after stopping infusion
• Must give IV (not subq) for acute thromboembolic disease
  • Unpredictable anticoagulation effect
  • Must monitor with PTT; therapeutic range is 1.5-2.5x normal value

See Also

• Unfractionated heparin reversal
• Coagulopathy (main)
• Low molecular weight heparin